Kerosene finishing process



Sept. 8, 1953 L. J. BLATz KEROSENE FINISHING PROCESS Filed May 26, 1949 @5kb .bcOo NOW UGQQOLW WZNWOQN* tokm. Nom.

UQQNN NOM patent-ed Sept'. 8*, 1953 KEROSENE FINISHING PROCESS Leo J. Blatz, Elizabeth, N. J., assignor to Standard Oil Development Company, a corporation of Delaware Application May 26, 1949, Serial No. 95,401

4 Claims.

. ment with a solid adsorbent.

At the present time a great deal of the kerosene produced is utilized in a variety of appliances equipped with a Wick. Thus, even at the present, a considerable quantity of kerosene is used for lighting and for heating purposes. Many kerosenes as obtained from the conventional refining of petroleum oils tend to deposit hard, carbonaceous material on the Wick during burning. This material tends to clog the pores of the wick and consequently to reduce the size of the llame;`

concomitantly the light and heat output of the iiarne are reduced. In addition this carbonaceous material tends to cause smoking. Consequently, an important characteristic of kerosene is a low char forming tendency, so that the indicated diiiiculties may be minimized. It is the particular object of this invention to provide a kerosene refining process yielding kerosenes having substantially reduced tendencies towards forming wick char. V

At the same time it is the broader object of this invention to provide a kerosene finishing process which will similarly improve other characteristics of kerosene. For example, the process of this invention is also adapted to reduce the sulfur content of the kerosene,to increase the smoke point of the kerosene and to improve the color of the kerosene. In connection with these characteristics, the process of this invention is particularly elicacious in improving the color of kerosene.-

i The kerosenes to which this invention has application are clearly those kerosenes which are not of suitable characteristics as obtained by the conventional refining of crude oils. For example, the Middle East crude oils are of such a nature that the kerosenes obtained by fractionation of thesecrudes are not of desirable characteristics, particularly with regard to Wick charring tendency, sulfurA content, and color characteristics. While the particular constituents of these crude oils, which result in the production of unsatisfactory kerosenes, cannot be successfully identified, it is believed that a correlation exists between the sulfur content of the crude oil, and the quality of the kerosene obtained therefrom.

Thus typical Middle East crude oilsfrom which, as indicated, high quality kerosene can not readily be obtained, have sulfur contents of 1.4%, or greater. It is, therefore, contemplated that the invention is of particular application to kerosenes obtained by the fractionation of crude oil having a sulfur content above about 1.4%, and particularly to the Middle East crude oils.

Alternatively, the feed stocks to be subjected to the process of this invention may be defined as kerosenes having undesirable Wick char, and color characteristics. Thus at the present time it is generally considered that to be of competitive quality in Wick char critical marketing areas kerosene should have a wick char value of l0 or less, as determined by the test method 10-44 of the Institute of Petroleum. In this test a sample of the kerosene is burned in a standardized type of lamp, under specified conditions. The char is then recovered from the Wick, measured quantitatively, and the result expressed as vmilligrams of char per kilogram of oil burned. Consequently,

it may be stated that the process of this invention is applicable to the treatment of kerosenes having a Wick char value of l0, or higher.

While attempts have been made to determine which constituents of kerosene result in a high char value, these attempts have not been successful. At the Apresent time `the constituents which result in a high char value have not been successfully identified. In this connection rit has been determined that the inorganic Vcontent of the kerosene is apparently not a factor, as a series of kerosenes having substantially the same ash content can have widely varying Wick char values. Data of this nature clearly shows a lack of any consistencybetween the amount of ash, or

inorganic material and the char forming tendency. Similarly by considering the effect of blending a wide variety of compounds in kerosene as regards their effect on the Wick char Value of the kerosene, no definite conclusions could be formed. Aromatic compounds vary widely in their tendency to form char without any apparent correlation between char formation and aromatic structure. Olenic compounds again appear to have some undesirable iniiuence on char formation, Whilek sulfur` and nitrogen compounds also appear to be' at least in'l part'causative of wick charring. Inany'case, the'reason for wick charring has not been sufticiently identied to permit application of any of the conventional methods for removing particular constituents from the kerosene. or to enable the prediction of the effect of a particular process on the wick char A value of a kerosene. f

However, in accordance with this invention it has been discovered that the properties of a kerosene, and particularly the wick char characteristics of the kerosene may be markedly improved by a two step treatment, involving a first stage treatment with sulfur dioxide followed by a second-stage treatment with a solid adsorbent. In general the conventional methods of sulfur dioxide treatment, and solid adsorbent treatment may be adapted to this process. Thus, any suitable means of contacting the kerosene to be treated with sulfur dioxide and subsequently with a suitable solid adsorbent may be used.

As indicated, the treatment Yof kerosenesr with sulfur dioxide in the first step of the process of this invention may be conducted according to conventional sulfur dioxide treating techniques. It is preferred, however, that the sulfur-dioxide treatment be carried out` by a liquid phase'contacting of the kerosene in a counter-current type of extraction tower. In such a process, liquid sulfur dioxide may be charged to the top of a treating zone, while the kerosene to be treated may be introduced to the bottom of the treating zone. The sulfur dioxide will then drop downwardly through the less dense kerosene which will move upwardly through the sulfur dioxide. Unpacked towers may be used as the contacting environment, or packing of Ya wide Variety of types can be employed, or perforated plates can be utilized. The conditions of temperature and pressure under which theV sulfur dioxide contacting is carried out are generally about -40 to +25"` F. and to 100 p. s. i. While the ratio of the` sulfur dioxide to oil is clearly avfunction of the extent of kerosene improvement desired, it is preferred that treats of about 25% to 169% be used. The kerosene rich phase separatingr after treatment with the sulfur dioxide, called the raninate, may then be subjected to. treatment with a solid adsorbent to secure the finished kerosene.

.Suitable solid adsorbents which V.may be used are bauxite, silica gel, charcoal, iron oxide orv adsorbent clay. However, it is preferred that adsorbent clay, such as fullers earth, or vbauxite be used as the solid adsorbent inthe process of this invention, as materially better results are obtained by using either of these two specific solid adsorbents. Again, any'. suitable method for contacting the solid adsorbent with the kerosene may be used. VOne of vthe simplest manners of conduting this operation is, tocontain the adfsorbent in granular form as a bed in a suitable vessel through which the kerosene to be treated may be passed. Alternatively, if desired, the solid adsorbent inv finely divided form may be mixed as a slurry with the kerosene. VIn `gen-- eral it is suitable to utilize ambient temperature and atmospheric pressures for the treatment, although elevated te-mperatures and pressures may be used if desired or convenient due to process conditions encountered. While the quantity of adsorbent used to treat the kerosene isY determined largely by the improvement desired, it is preferred to utilize a quantity ofv about 0.1`to 4 lbs. absorbent per barrel'of oil and preferably about one pound of adsorbent per barrel of oil treated, at feed rates of about`0.25y to 4 volumes of oil per volume of adsorbent. per hour. While no part of this invention, the adsorbent usedY may be regenerated for continuedv Vuse, in the process by steaming, drying, and roasting, or byv washing with quantities of a widevariety of washing agents as in conventional adsorbent r` generation systems.

While, as heretofore described the process of this invention comprises the combination treatment of the kerosene with sulfur dioxide followed by treatment with a solid adsorbent, it is apparent that many modicationsof this process may be made. Thus, for example, in the case of extremely high sulfur kerosenes it may be desirable to subject the kerosene to additional treating steps to further reduce the sulfur content. For example, acid treating, hypochlorite sweetening, or Doctor sweetening, as these processes vare identiiied in the petroleum industry, may be utilized,'in addition to the particular processing steps of this invention. In the pre- Y ferred embodiment of this invention, after the Y kerosene has been treated with sulfur dioxide it is subjected to a process for conversion or removal of mercaptans to improve odor, and thereafter the kerosene is treated with a solid Vadsorbent. Again, minor alterations of the-process may be made involving for example particular washing techniques for the kerosene. In this connection it is generally preferred that the raffinate obtained from the sulfur dioxide treatment be subjected to a water wash followed by a caustic wash, and followed by a second water wash, although other washing techniques may be used if desired. Apparently, the particular technique used for washing the kerosene during, or after the processing steps of this invention does not materially affect the wick char value of the kerosene. As an operating expedient, the kerosene should be free of moistureprior to contacting the adsorbent material. i

The process ofthis invention maybe understood by reference to the accompanying drawing indicating a diagrammatic now plan of one embodiment of this invention. Referring *tov this drawing, the numeral I designates a treating zone in which kerosene may be contacted with sulfur dioxide. current liquid-liquid extraction tower as illustrated in the drawing. In this case liquid sulfur dioxide will be withdrawn from areservoir 2 and will be introduced near the top of tower l, while kerosene may be removed from reservoir 3 for introduction vnear the Vbottom of` zonev I.

Inthe embodiment illustrated in the drawing, extraction tower l is shown as containingv apacking material suchV as Raschig rings, or similar packing. This packing ordinarily does,Y notA ex.- tend completely to the top or bottom of the tower, as free space is maintained near the top and bot.- tom of the tower for phase separation. Inthe operation of an extraction tower, such-as thatA illustrated, the oil` introduced through line- ,4- flows upwardly through the tower counter-currently to a flow o-f sulfur dioxide introduced. atY

The Ina-V the top of the tower through. line 5. terial reaching the top of the tower is permitted to separate into two phases in the portion of the. tower above line 5, to yield a raffinate phase consisting substantially of kerosene. Similarly, ther material at the bottom of the tower'i-s. permitted to settle in the free area of the tower below line 4 to yield a lowermost phase consisting. principally of sulfur dioxide and identined as 'the extract phase.l The extract phase may be withdrawn from the bottom of zone l through line 6 for disposal as desired. Generally, theextract phase is subjected to distillation to permit recovery of sulfur dioxide `which may be recycled into ,the process. The extract product obtained Zone I may consist of a counter-v from this distillation is rich in aromatics and sulfur compounds and may be profitably used after desulfurization as a superiorblending agent for tractor fuel. Similarly, the raffinate phase obtained through line 'I at the top of tower I may be conducted to a .distillation zone 8 operated `so as to remove sulfur dioxide overhead through line'S for recycle after liquefaction and cooling` to zone 2. The treated kerosene, or the raflinate product is then withdrawn as a bottoms product from still 8 through line I0. While an optional feature of the process of this invention, as applied to many kerosenes it is preferred that the rafiinate product of line I be subjected to a hypochlorite treatment in zone II in the event that the kerosene being treated contains noxious odored mercaptans. Thus, if the kerosene railinate contains over about 1 mg. of mercaptan sulfur per 100 ml., it is preferred that the raffinate product of line I0 be subjected to hypochlorite sweetening in zone VI I. Again, any ofthe con- `lentional methods of conducting the hypochlorite treatment may be used. It is presently contemplated that a preferential Vtreatment may be obtained by treating the raffinate product of line I0 in zone II with about 1-10 volume percent of hypochlorite solution containing about 2-30 grams per liter of sodium hypochlorite, and more than about two grams per liter of free caustic. As diagrammatically illustrated in the drawing, the kerosene may be hypochlorite treated in a mixing and settling system comprising the orifice mixer 25 and settler II. The hypochlorite sweetened kerosene may then be removed from the upper portion of zone II through line I2 for treatment with a moisture removing or coalescing this data.

l EXAMPLE II A kerosene having a boiling range of 320 to 550 F. obtained from the distillation of mixed sweet crude oils and subjected to the Doctor sweetening process had a wick char value of 36 ing/kg. This feed stock was then filtered through Attapulgus clay or fullers earth under identical conditions to those given under Example I. The kerosene was then found to have a wick char value of 33 mg./kg.

It will be noted from this example, as in the caseof Example I, that clay, or adsorbent treatment alone does not significantly improve the wick char characteristics of kerosene.

EXAMPLE III A kerosene having a boiling range of V355 to 518o F., obtained from the distillation of a Middle East Kuwait crude oil had a wick char valueof EXAMPLE 4 Y Awkerosene having a boiling range of `357 to agent such as sand, in vessel I3; coalesced water being withdrawn through line I4, and dried kerosene passing through line I5 to treatment with a solid adsorbent in zone I6. Zone I6 ma5" consist of a tower, or vessel substantially lled with a solid adsorbent through which the kero-v sene is passed at flow rates of about 0.25 to 4 volumes of kerosene per volume of adsorbent per hour and at existing temperatures and pressures. f

As indicated, it is preferred that the adsorbent consist of either bauxite or fullers earth. The

finished kerosene is then obtained from the proc- I ess through line I'I leading from the solid adsorbent treating zone.

The treatment of the kerosene by the two stage pro-cess disclosed will improve the wick char value of the kerosene, and will improve the color and other properties of the kerosene.

As examples of the effectiveness of the process of this invention, and to aid in a more thorough"vv` understanding of the invention, data will be given relative to the treating steps of the process.

EXANLPLE I A kerosene distillate boiling in the range of 300 to 525 F. as obtained from a Bradford crude oil had a wick char value of 20 mg./kg. In this stantially no improvement of the wick char value. the kerosene resulted from the solid adsorbent 512 F. obtained from an4 Iraq crude loil initially had awick char value of 46. After treatment with fullers earth, Vemploying the conditions in-v dicated in Example I, the wick char value was reduced to 32. This same kerosene when treated with by volume of sulfur dioxide at 15 F., according to the conditions of Example III, had a wick char valueof 25. However, when this kerosene was treated with sulfur dioxide, .and subsequently treated with Attapulgus clay, according to the same treating conditions, it was found that the wick char value had been reduced to 6. -Again, it willbe noted from this example that while neither clay treatment alone, or sulfur dioxide treatment alone were suitable to reduce the wick'char value to a low value, the combination treatment of sulfur dioxide extraction and adsorbent percolation was successful in producing a kerosene o f low wick char value.

` As further examples of the process of this invention, kerosenes obtained from a variety of Middle East crude oils were subjected to sulfur dioxide extraction and then treated with a variety of solid adsorbents. The inspections of the crude oils employed in these tests, and the kerosenes obtained from these crude oils, are given in Table I', below.

`These kerosenes were then treated as indicated in Table II, wherein the operating conditions are given together with the inspections of both the feed and the raffinate product. Again, it will be noted from Table II, that the sulfur dioxide extraction, while resulting in some improvement of the kerosene characteristics did not lower the wick char value below 10.

The raffinate products identified in Table II,

` Maximum Kerosene Fraction (300 ZET-580 adsoieoent treatment renewing the initial einer t dioxide treatment was successful towering the Table 1.-'Inspectz'ons of Mz'clclle VI i'ast 'etudes and lceros'enes therefrom Cuntry raq Kuwait.

Crude: Y p M y,

Gravity, API 36,1 32,7. Sulfur, percent 2.00. v2.55.

Yield, percent (VOL). Gravity, AP-1 Sulfur, percent.- Smoke Point, m

Fe'ed Stock Kuwait Kerosene Operation Conditions:

Percent SO2 Treat Extraction Temp., "F

Rainate Yield, lereent Smoke point, mm.

1Treating carried out in counter-current packed tower GS in Example III.

ro, 4and 'tnereafter .oontacting the' -said raffinate product with 'about O ito .4 pounds 'of la *solid 'ad'- sorbent 'per Ybarrel 'of oil. v

l2. The process fior producing kerosene corn-V prising thesteps -of .fractionating -a Middle East erud'e oiil:containingV morethan about 1.4% sulfur and segregati'ng fa kerosene fraction boiling in tnerange 'of about 300 to 580 F., contacting said kerosene fraction in liquid phase with about to 100%byvolume lof sulfur dioxide at a. temfperature olf about 40 to +25 F., and a pressure of about 0 to I10013. s. i. to obtain a rainate prod uct, fcha'ra'cteri'ze'd by fa wick char value Ygreater than about 10, and thereafter contacting the said raiiinate product in liquid ,phase with `about 0.1

to 2i' pounds of 'adsorbent clay per Vbarrel of oil.

3. The processzof 'providing high qual-ity kerosene in which a kerosene boiling in the range of about 300 to `580" F. derived from a Middle East crudexoil lhaving a vsulfur content -g'reater than about v1.4 is contacted with sulfur dioxide lin liqud'phase at a `teiriperature of about 40 to +25 F., anda pressure of about 0 to 100 p. s.i. to obtain Aa` 'raiiinate product characterized vby a Wick chai value above about 10, and a rnercapt'an content greater than about l Ing. of mercaptan sulfur per "roo inl.. oontactingsaid raiiinate prodnot with' about 1 to 10 volume percent of an taoting the Asaid -treatedrainate product with about 0:1 to 4 pounds of a solid adsorbent per barrel of oil.

` Table YI+II.-'Reducim of wick char by adsorbent Y percolation at room temp.

[Feed stocks represent raiin'ates from 100% counter-current SO2 extraction of Y respective crude] Sample Period Sample 1 2 3 4 5 `6 Kuwait thru Fullers earthcl Y Yield atend of period, B/T. Y 0 (Feed) u 215 434 WickChar 16 l 7 ,4- Saybolt Color +13 +30 +30 Iraq thru Fuiler's earth:x f

Yield at end o period B 0 (Feed) 201 435 Wick Char 17 ,'9 9 Saybolt Colo +30 Kuwait thru Bauxitul Y Yield at end of period, B/T 0 `(Fe'ed) 147 304 Wick'ChaL 16--.- 7 5 Saybolt Color +13 +30 Iraq thru Beuxiteil Y Yield at end joffperiod, B/T---" 0 (Feed) 150 303 Wick Char 17 f- -6 3 Saybolt Color +4 +30 +30 Kuwait thru Silica Gel (20/40 mesh):

Yield at end oi period, B/T 0 l(}3`eed) 304 571 Wick Char 16 1l Saybolt Color. +13 Kuwait thru Charcoal (l0/20 mesh): n

Yield at end of period, B/T 0 (Feed). 842 Wick Char 16 7' 9 Saybolt Color +13 +30 +28 Kuwait thru Viron Oxide (1o/20 261 525 C 9 Saybolt Color.

l 30/60 mesh fresh clay' or' bauxite rsedvinv all eases; dehydrated at 800 F.`fo' ou hour prior to usage.

'abDt 75 about 4. process for providing d kerosene ersat-` isfactoryY burning duality derived from' a Middle East crude oil having a 'sulfur content of Y1.4% or greater, 'comprising the steps of contacting said kerosnein liquid. phase with about 25% to 100% byvolurie of sulfur dioxide at a tempera-f ture of about -40 to -|-.25 F., and a pressure oi about 'oto loop. s. i. `to obtain a raiiinate product characterized by a wick char value greater than 1o, and thereafter contacting the said alkali vr'netal li'ypochlorite, and thereafter oon--V rail-mate product with about one pound of a solid Number Name Date adsorbent per barrel of oil at ambient tempera- 1,885,524 Lazar Nov. 1, 1932 tures. 2,488,855 Denton Nov. 22, 1949 LEO J. BLATZ. 2,560,330 Brandon July 10, 1951 5 References Cited in the 111e of this patent OTHER REFERENCE? UNITED STATES PATENTS Kahchevsky and Stagner, Chemlcal Rening of Petroleum, 2nd ed., pages 316, 318 and 3'19, Number Name Date A. C. S. Monograph Series No. 63, pub'. by Ren- 1435f824 Dulsan NOV- 14, 1922 10 hold Publishing corporation, New York, 1942. 1,791,941 stem Feb. 1o, 1931 

1. THE PROCESS FOR PROVIDING A KEROSENE OF SATISFACTORY BURNING QUALITY DERIVED FROM A MIDDLE EAST CRUDE OIL HAVING A SULFUR CONTENT OF 1.4% OR GREATER, COMPRISING THE STEPS OF CONTACTING SAID KEROSENE IN LIQUID PHASE WITH ABOUT 25% TO 100% BY VOLUME OF SULFUR DIOXIDE AT A TEMPEATURE OF ABOUT -40 TO +25* F., AND A PRESSURE OF ABOUT 0 TO 100 P.S.I. TO OBTAIN A RAFFINATE PRODUCT CHARACTERIZED BY A WICK CHAR VALUE GREATER THAN ABOUT 10, AND THEREAFTER CONTACTING THE SAID RAFFINATE 